Segment and Geographic Information and Significant Customers - Location of Long Lived Assets Including Intangible Assets and Goodwill (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Sep. 30, 2018
Revenues from External Customers and Long-Lived Assets [Line Items]
Total long-lived assets	$ 4,110,580	$ 4,014,251
UNITED STATES
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-Lived Assets	3,279,186	3,031,714
International [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-Lived Assets	$ 831,394	$ 982,537